Idea dump

Luna walked into her room. She was finnaly aging. Unlike most ponies who got old and wanted to rush though life Luna had done everything she wanted to. Her daughter would be truly immortal living forever more. Luna's mane no longer resembled the night sky. Instead in looked like it did when she was younger. She entered the room and saw her husband Supernova lying on the bed. "Hello there Supernova. Are you ready to fly?" Luna said joking.

"I'm not ready to die yet. Besides you don't have that many years left yourself." He replied

"Ha! True. Well I came to say goodbye. Deny it all you want but as soon as the sun rises your gone." Luna said.

"Well Luna I am glad to say that I was your husband. I am also glad that Nidra is happy." He said satisfied. "Luna can I ask for one final request?"

"Name it."

Could you spend one final night with me?"

"Of course I will."

Then the two spent their final night togther watching the sun rise.